1. Field of the Invention
The present disclosure relates to a transparent display device, and more particularly, to a transparent display device for minimizing external environmental effects, which have an effect on an image, such as color background overlapping, interference due to external light, and the like in order to provide an original image with no distortion to a viewer.
2. Description of the Related Art
In the flat panel display device field, studies on a transparent display device through which an image displayed on a display panel as well as an object disposed at a rear side thereof are visually recognized have been carried out.
Among flat panel display devices, in general an organic light emitting diode (OLED) display device using a spontaneous emitting element may be divided into a light emitting area and a rear reflective area, and thus it is advantageous to implement OLEDs in transparent display devices. However, a liquid crystal display (LCD) display device using an additional backlight unit, due to the non-spontaneous light emission characteristics thereof, may provide a transparent display area displayed with an image, and be affected by a background at the rear side or indirect light while displaying an image which overlaps the light emitted from the background with the image, causing the problem that the image is displayed in a color different from the intended color. Furthermore, the contrast may decrease due to an interference of indirect light, thus reducing the visibility of the image.
FIG. 1 is a view schematically illustrating various interference factors having an effect on a transparent display device in the related art.
Referring to FIG. 1, according to a transparent display device 1 in the related art, a viewer may view a background 5 located at a rear side of the transparent display device 1 while at the same time viewing an image 2 having R, G, B primary colors from a front surface of the display panel. In other words, the viewer may view an image and an object according to light (i1) due to an original image 2 displayed by the transparent display device 1 and light (i2) that has passed through the transparent display device 1 and arrived at the viewer's eyes.
However, light (i3) due to the background 5 may have an effect on the color of the original image 2 and the color of the background 5 itself may distort the original color.
Furthermore, in the transparent display device 1, there exist a front light source (FL) and a rear light source (RL) with respect to a front side of the display panel, and it may be a cause of interference or distortion with respect to light (i1, i2) from the intentional image and object.
For an example, light due to the front light source (FL) and rear light source (RL) may enter a front surface and a rear surface of the transparent display device 1 to have an effect on the hue, brightness and chroma of the background 5, thereby allowing the viewer to view distorted light (i4, i5). Furthermore, part of the light (i6) emitted from the rear light source (RL) may distort the hue, brightness and chroma of the background 5, thereby having a direct or indirect effect on the light (i4, i5).
In other words, contrary to an existing non-transparent display device, a rear background may be visually recognized through the display panel on the transparent display device, and thus the brightness and chroma of the background may overlap and interfere with that of an original image, thereby serving as an impediment to viewing the image and object.